Flow rate meter incorporating reusable device

ABSTRACT

A flow rate meter comprises a disposable fluid transport portion and a reusable interface connector removably attached to the transport portion. The transport portion includes a flow conduit having an input and an output, while the interface connector provides feedback to a desired location. First and second portions of control circuitry are, respectively, associated with the transport portion and the interface connector. The first circuitry portion includes a plurality of electrodes and derives flow rate. The device measures a range of flow rates and is adapted, for example, for use in micro-fluidic systems including fluids administration to a patient&#39;s body.

FIELD

The present invention relates generally to a device for monitoring massflow rates. In particular the invention relates to an economicallypractical means for monitoring mass flow rates in a cost sensitiveenvironment such infusion therapy.

BACKGROUND

Several advanced flow monitoring solutions have been invented over theyears:

One such approach (Miller, Jr. et al., U.S. Pat. No. 4,532,811) appliesa thermal pulse to a stream of fluid and has a single downstream heatsensor to sense the thermal pulse. The transit time between the heatingelement and the heat sensor determines flow velocity. The Miller thermalpulse technique is effective over a wide range of fluid temperatures,because the unheated fluid is used as a reference: the downstream sensordetects thermal pulses, i.e. envelopes of fluid traveling through theflight conduit that are warmer than the unheated fluid. Therefore, thethermal pulse technique is advantageously insensitive to changes inambient temperature.

Jerman, et al., U.S. Pat. No. 5,533,412 present an improvement toMiller's approach by providing at least two spaced apart sensors locatedalong the flight conduit downstream from the thermal marking positionand the flow velocity is derived from the time it takes the pulse totravel between two sensors.

Mosier, et. al., U.S. Pat. No. 6,660,675, and continuation in partHarnett, U.S. Pat. No. 7,225,683, disclose a device for measuring fluidflow rates over a wide range which operates by marking the fluid byproducing compositional variations in the fluid (pulses), that aresubsequently detected downstream from the marking position to derive aflow rate. Each pulse, comprising a small fluid volume, whosecomposition is different from the mean composition of the fluid, can becreated by electrochemical means, such as by electrolysis of a solvent,electrolysis of a dissolved species, or electro dialysis of a dissolvedionic species. Measurements of the conductivity of the fluid can be usedto detect the arrival time of the pulses, from which the fluid flow ratecan be determined. A pair of spaced apart electrodes can be used toproduce the electrochemical pulse mark.

To the knowledge of the inventor, none of the above inventions arebelieved to have resulted in practical commercial products, particularlyfor medical infusion where the medical tube sets are disposable, andintegrating the above listed flow monitoring technologies in adisposable administration set is economically impractical.

U.S. Pat. No. 7,096,729 for Repko and al attempts to address theeconomical disadvantage of the above prior art by disclosing adisposable fluid flow sensor, which generally includes a flow channelassembly comprising a flow channel tube in association with a disposableflow channel portion. A sensor die is located proximate to a thininterface or membrane formed from the disposable flow channel portion,such that the sensor die measures a flow of fluid flowing through theflow channel tube and the disposable flow channel portion of the flowchannel assembly. What Repko refers to as a “disposable sensor” isactually a portion of a tube designed to externally receive anon-disposable sensor. In Repko's technology the sensor do not come indirect contact with the flow media (here after sometimes referred to asnon-invasive vs. invasive) and therefore can introduce error due to a)variations in the flow conduit properties in particular those of thebarrier (referred to as membrane in Repko's) between the sensor die andthe flow media, b) variation in alignment between the flight tube andthe sensor's die, c) user errors in replacing the sensor dieappropriately and no means for detecting this error, and d)environmental effects such as dust or other contaminants, moisture andwetness, impressions of greasy fingers or talc from a nurse's gloves, e)loss of signal or information in the barrier (membrane) even at optimaloperation conditions. Perhaps the most critical disadvantage of Repko'sfor critical flow measurement application such as medical infusiontherapy is that an error or malfunction due to the above list of causesof errors can not be detected, and therefore can not be corrected for,while also can not alarm the medical staff.

Sage et al., U.S. Pat. No. 7,361,155 attempts to address some of theabove disadvantages by disclosing a device that comprises a flow channelthrough which the liquid flows. During manufacture or at some otherpoint prior to the delivery of the liquid, the flow channel ischaracterized in terms of one or more properties of flow of a liquidthrough the channel. This characterization is stored in such a way thatthe flow channel characterization is available to the liquid deliverydevice at time of use. At time of use, the liquid delivery system readsthe stored flow channel characterization and uses the stored flowchannel characterization for safe and accurate delivery of the liquid.While Sage' addresses the first disadvantage listed above for Repko's(marked as “a” in the previous paragraph) it fails to address the otherdisadvantages which are not related to manufacturing variations of theflow conduit. In particular Sage does not propose detecting and alarmingfor malfunction. More than anything, Sage's invention enlighten theproblem need to be addressed to create an accurate and reliable devicefor measuring flows in disposable fluid transport systems which areeconomically practical. Sage's additional disadvantages is thatcalibrating each sensor, registering the calibration information on eachindividual sensor, and having delivery systems being equipped to readand process said registered information bare significant costs which arenot desirable and usually not acceptable in medical care practices.

It is therefore the object to provide an economically practical flowmeasuring device for accurate and reliable flow monitoring in a fluidtransport device.

It is another object to provide a flow measuring device that identifieshuman errors and malfunction and take measures to alarm a device or aperson and to avoid harm or damage to a system, a patient, or a processor procedure.

It is another object to provide a flow measuring device that monitorflows in a fluid transport device in proximity to the outlet of saidfluid transport device, and in particular where no possibledisconnections may occur between the measuring position and the outletof said fluid transport device.

It is another object to provide a flow measuring device that feedback toa flow control device which controls the flow in said fluid transportdevice, to improve the flow administration regime and to warn abouthazardous conditions.

It is another object to associate a flow control device with the flowmeasuring device of the present invention.

It is another object of the present invention to provide safety meansfor preventing flow in the fluid transport device if the flow controldevice is suspected to malfunction.

SUMMARY

According to aspects of the disclosure, and as contemplated by the twodiagrams below, a flow rate meter comprises a disposable (also referredto herein at times as “durable”) fluid transport device portion that aflow conduit having an inlet and an outlet, with the flow conduitdefining a flow channel. The disposable portion also includes at least afirst portion of a control circuitry which is operative to derive theflow rate, wherein the first portion includes a plurality of electrodesadapted to directly contact fluid when present within said conduit. Areusable interface connector removably attaches to the disposable fluidtransport device portion. This connector includes a second portion ofsaid control circuitry and a communications interface for establishingfeedback communication to a desired location.

According to another aspect a flow measuring device (here after sometimes referred to as “flow meter”) is provided for monitoring mass flowrates comprising: a) a portion of a fluid transport device, b) a durabledevice associated with the fluid transport device during the course ofoperation, c) a flow sensor, and d) electronic circuitry to operate saidflow sensor where:

-   -   the portion of said fluid transport device comprises at least        part of the flow sensor, the sensor comprises: a flow conduit        associated with the flow media of the fluid transport device; at        least part of the electronic circuitry (here after the        “disposable circuitry”) and is invasive to the flow media by at        least two electrodes in direct contact with said flow media.    -   the durable device comprises at least part of the electronic        circuitry (here after “durable circuitry”)

The arrangement is such that:

-   -   The durable device operates the sensor and provides at least        part of processing of the sensor signals to data,    -   The durable device communicates said data with a device or a        person. The durable device can be reused when the fluid        transport device is discarded.

The durable device (also interchangeably referred to herein as areusable device or portion) can comprise part of a system such as a kitincluding a non-disposable portion and two or more disposable portions

The flow meter allows for economically practical and reliableimplementation of a flow measurement in a disposable fluid transportdevice.

Further, the flow meter does not require calibration due tomanufacturing variants or environmental conditions (as described above).

Yet further, the flow meter is not sensitive to mislocation ormisalignment between the durable unit and the disposable unit, and candetect human errors or malfunction, and alarm, or take further actionsdue to that detection.

Yet further the flow meter does not suffer from losses of signal orinformation which non-invasive flow meters are sensitive to, associatedwith working through a barrier.

It also enables a small form factor, and thereby allows for locating thesensor in proximity to the desired position for reading the flow, forinstance as in proximity to the injection site.

A system is also described for controlling mass flow rates in a fluidtransport device comprising a flow meter as described above formeasuring flow rates in said fluid transport device, and a flow controldevice for controlling the flow rates in said fluid transport device,wherein the data generated by the flow meter is used to adjust said flowby said flow control device.

The above arrangement allows for economic practical implementation of amedication infusion system. It also allows for locating the sensor inproximity to the desired position for reading the flow, such as inproximity to the injection site.

Monitoring flow rates generally refers to precise measurement of flowrates as well as precisely sensing the existence or absence of flow.

Several mass flow metering technologies are applicable for the presentinvention:

In one preferred embodiment the flow meter is a Composition VariationTime-Of-Flight (TOF) Mass Flow Meter (MFM) as disclosed by U.S. Pat. No.6,660,675 and U.S. Pat. No. 7,225,683, incorporated here by reference.These TOF MFMs refer to a device for measuring fluid flow rates whichoperates by marking the fluid by producing compositional variations inthe fluid, or pulses, that are subsequently detected downstream from themarking position to derive a flow rate. Each pulse, comprising a smallfluid volume, whose composition is different from the mean compositionof the fluid, can be created by electrochemical means, such as byelectrolysis of a solvent, electrolysis of a dissolved species, orelectrodialysis of a dissolved ionic species. Measurements of theconductivity of the fluid can be used to detect the arrival time of thepulses, from which the fluid flow rate can be determined. A pair ofspaced apart electrodes can be used to produce the electrochemical pulsemark, while another pair of electrodes can be used for detection of thepulse.

The mass flow rate meter could also be constructed according to any ofthe embodiments described in my co-pending U.S. application Ser. No.12/350,897 filed Jan. 8, 2009, or my co-pending PCT application SerialNo. PCT/US09/30494, also filed on Jan. 8, 2009. These applications arealso incorporated in their entireties.

The fluid transport device generally refers to any means forcommunicating fluid media between a source or a number of sources and atarget or a number of targets. The fluid transport device may comprise ahose, a tube, a pipe, a fitting, a connector a wick, a channel, aconduit, a groove, a trench, an enclosed path machined in a circuitboard a chip or a wafer, a device implemented in the flow pathcommunicating the upstream and the down stream portions of the fluidtransport device, a port, a nozzle, a spout, a needle, a canula, acombination of the above or any other means known in the art. The fluidtransport device can be connected to additional fluid transport devices.

In one preferred embodiment of the present invention the abovecomposition Time-Of-Flight is implemented by incorporating a disposableflight conduit section in the fluid transport device. The flight conduitestablishes fluid communication between two portions of the fluidtransport device. The flight conduit comprises at least a portion of thedisposable circuitry comprising at least two pairs of invasiveelectrodes in direct contact with the flow media—one pair for generatingthe mark and another pair spaced apart downstream from the first pairfor detecting the mark. In one embodiment one electrode of each pair ofelectrodes is common thus reducing the actual number of electrodes tothree. The disposable circuitry is associated with the durable (i.e.reusable) circuitry by communication channels and/or powering channels.In one embodiment contact tabs extend from said portion of said fluidtransport device which come in contact with the durable device toassociate said disposable circuitry with said permanent circuitry. Inanother embodiment said association is wireless. In one embodiment thedisposable circuitry is merely the sensor electrodes and conductivetraces communicating said sensor electrodes with said contact tabs tothe durable device. In another embodiment the disposable circuitrycomprises filters and/or other elements to modulate, clean, or partlyprocess the signals.

In another embodiment the disposable circuitry comprises an RFIDcircuit. In a further embodiment the RFID circuit is used to powerand/or communicate signals and data. In one embodiment said disposablecircuitry comprises an element that identifies that the fluid transportdevice has been previously in use, such as a fuse that is burned duringthe first operation of the flow meter. The durable device comprises thecircuitry for operating said electrodes, optionally processing thesensor signals, and communicating said signals or data to a person or adevice.

In one embodiment said data is communicated to a display panel such as aseven-segment display, an LCD display, a video monitor, etc. In oneembodiment said display is integrated in the durable device. In anotherembodiment the durable device comprises visual and/or audiblecommunication means with a person (such a LED and/or buzzer) providingflow rates values, information on the functionality of the system aswell as warning indications.

In another embodiment the data is communicated to a flow control devicewhich controls the flow in said fluid transport device, to enhance thecontrol of the flow rates in a closed-loop control fashion, or to warnof hazardous conditions. Said communication means can be (but is notlimited to) one of the communication means known in the art includingRF, IR, Ultrasonic, or hard wired. In one embodiment said communicationwires are integrated in the tube of the fluid transport device such asby co-extrusion. Flow control devices include, but are not limited to:peristaltic pumps, syringe pumps, pressurized bladders (balloons) withcontrollable flow restrictor, or gravitational delivery with flowrestrictor, or any other flow control devices known in the art.

In one embodiment said flight conduit is a segment of a tube of thefluid transport device. In another embodiment the flight-conduit is afitting inserted between two segments of the fluid transport device. Inanother embodiment the flight conduit is implemented in the peristalticpumping portion of a dedicated peristaltic pump set. In anotherembodiment the flight tube is implemented in the exit port of a syringe,an infusion bag, infusion bottle, or similar device. In one embodimentthe flight conduit is implemented in an infusion bag/bottle spike. Inanother embodiment the flight conduit is implemented in a portion of aninvasive device (such as a needle or catheter) thereby further reducingthe risk of discrepancies between the actual flow delivered from thefluid transport device and the measured values, and in particularreduces the risk of such discrepancies due to disconnections in thefluid transport device due to human error, kinks in the tube, occlusionof the administration device, etc.

In one embodiment, this invention represents a system comprising a kit,which includes one durable device and at least two fluid transportdevices. In such a kit, the fluid transport device may be the same, ormay be different from each other. In a preferred embodiment, the durabledevice comprises the user interface and control electronics of thesystem.

In one embodiment the system comprises at least two disposablecomponents comprising flow channels that are different from each other.In a preferred embodiment, these channels differ in design, so that theymay, for example, be optimized in geometry to measure different rangesof flow rate.

In a further preferred embodiment, these flow channels comprise meansfor identifying one design from another without involvement from theuser. In one example, the channels comprise tabs that make electricalcontact to a non-disposable component, and the specific geometry of thetabs serve in part to establish the identity of the disposablecomponent. These tabs may be electrically connected to the sensing orwrite electrodes, or they may be electrically isolated from the channelelectrodes. In one embodiment, the tabs are isolated from the channelelectrodes, and when in contact with the non-disposable component closea specific circuit on the non-disposable component that verifies thechannel's identity.

In one embodiment additional detectors are incorporated in the flowmeter, for example: temperature, pressure, shock (G), air bubblesdetector, specific mass detector, concentration detector, or otherdetectors known in the art. In one embodiment the flow meter provides atleast part of the components for said additional detectors. In anotherembodiment at least part of the flow meter is incorporated in anotherdetector or device. In one embodiment, the flow sensor is implemented ina chip which incorporate other electronic sensors.

In one embodiment the flow meter is incorporated in a flow controlsystem that comprises means for shutting-off the flow in the fluidtransport device. In one embodiment at least part of said flow stoppingmeans is incorporated in the fluid transport device. In one embodimentat least part of said flow stopping means is incorporated in the durabledevice. In one embodiment the flow stopping means is a pinch valve whichhas a movable rigid section that can be advanced to press on a flexibletube portion of the fluid transport device, thereby causing said tubeportion to collapse and shut off the fluid passage. In anotherembodiment the flow-shutoff is a normally closed valve and the flowcontrol device manipulates said valve to open. The flow shut-off meanscan be activated if malfunction of the fluid transport device issuspected or detected. In another embodiment the flow control device isincorporated in the flow meter.

In one embodiment the flow meter is incorporated in a flow controlsystem that comprises means for regulating the flow in the fluidtransport device. In one embodiment at least part of said flowregulating means is incorporated in the fluid transport device. In oneembodiment at least part of said flow regulating means is incorporatedin the durable device. In one embodiment the flow regulating means is apinch valve which has a movable rigid section that can be advanced topress on a portion of a flexible tube of the fluid transport device,thereby causing said tube portion to collapse and narrow down the fluidpassage, thereby limiting the flow in the fluid transport device. Inanother embodiment the flow regulating means is a normally closed valvewhich is manipulated by the flow control device to proportionally open.In one embodiment the durable device can be set to a desired flow rateand maintain said rate accordingly. The flow regulating means isparticularly advantageous where the flow control device is merely aninfusion bag or a balloon (together “passive infusion devices”). In oneembodiment a Human Machine Interface (HMI) panel allows for setting ofthe desired flow rates for said flow regulator and alerting conditionsat which alarms will be activated and the flow through said flowregulator will be halted.

The durable device can be powered by one of the means known in the artincluding, but not limited to: AC wall power, DC, battery, arechargeable battery, a photovoltaic cell, a motion activated powergenerator, RF induction, RFID circuit or a combination of the above. Inone embodiment the durable device is operated (powered) by wires whichare embedded in the tubing of the fluid transport device. In oneembodiment said embedded wires are fed from a power source in the flowcontrol device. In another embodiment the flow control device is aninfusion pump and the fluid transport device is an infusion set, andsaid durable device is operated by a rechargeable battery, where saidflow control device comprises a dock for recharging the battery of thedurable device.

In a further embodiment the present invention comprises means forpreventing loss of the durable device pre- or post-use. In thisembodiment the durable device and/or the fluid control device comprisesmeans for sensing the distance range of one from another and a warningmeans to inform a person (visual and/or audible) or a device that thedurable device is too far removed from the flow control device.

The flow meter is not sensitive to miss-location or misalignment of thedurable device and the fluid transport device and as long as thecommunication between the durable circuitry and the disposable circuitryexists the accuracy of the measurement is not biased, not effected byenvironmental conditions, not effected by human errors, and does notrequire calibration. Lack of communication between the durable circuitryand the disposable circuitry can be immediately and reliably detectedand immediate measures can be executed to avoid harm or damage to asystem, patient, process or procedure

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 a-1 j each illustrate aspects of a preferred embodiment of thedevice of the present invention where the fluid transport device is anIV (intravenous) tube set.

FIGS. 2 a & 2 b demonstrate a preferred embodiment where part of thesensor is accommodated in a fitting in the fluid transport device.

FIGS. 3 a & 3 b demonstrate a durable device comprising HMI, and a flowregulator.

FIGS. 4 a & 4 b demonstrate a preferred embodiment where the durabledevice is accommodated in a drug delivery pump; and

FIGS. 5 a & 5 b schematically depict a preferred embodiment of a flowcontrol system.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1 a, a fluid transport device 11 is shown, in thefashion of an IV catheter set. The fluid transport device 11 comprises atube 17 terminating in a catheter hub 16. The catheter hub 16 isconnected to a fluid administration catheter 13 commonly in the form ofa stainless steel hypodermic needle or a soft cannula. The catheter hubcomprises a flight conduit 12 having a first end in fluid communicationwith said tube 17, and a second end in fluid communication with saidcatheter 13, said flight conduit 12 establishes a permanent fluidcommunication between the tube 17 and the catheter 13. Said flightconduit 12 provides portion of a TOF MFM. The tube 17 establishes afluid communication between the flight conduit 12 and a flow controldevice (not shown) which controls the delivery rates (flow rates) of amedication from a fluid source. Said flow control device can be any ofthe flow control devices known in the art including an infusion bag witha flow regulator, a pressurized bladder (balloon), a peristaltic pump, asyringe pump, micro-infusion devices, a MEMS micro fluidic pump, Osmoticpump, a syringe, etc. The tube 17 can be connected to the hub 12 bypressure fit, barb fitting, glue, heat sealing, Luer slip connector,Luer lock connector, etc.

The detail view in FIG. 1 b shows the hub 16 of FIG. 1 a. The hub 16comprises a portion of a Composition-Variation TOF MFM according to theoperation principal disclosed by U.S. Pat. No. 6,660,675 and U.S. Pat.No. 7,225,683 incorporated here by reference in their entireties. Twopairs of electrodes 14 are accommodated in the flight conduit 12 wallhaving a first end in contact with the fluid in the flight conduit (notshown) and a second end extending through the conduit wall to formconnector tabs to the durable device (not shown). The first pair ofelectrodes 14′ is accommodated at a first position along the flightconduit 12 (also referred to as “introduction location”), and is used asthe excitation electrodes or mark generator, and the second pair ofelectrodes 14″, accommodated spaced apart downstream from the first pair14′, capable of detecting said mark. The flow rate is analyzed from thetransient (or “flight”) time of the mark between the excitation time atthe first electrodes 14′ and the detection time by second pair ofelectrodes 14″, the distance between the first pair 14′ and the secondpair 14″ of electrodes, the fluid properties, and the cross section ofthe flight conduit 12. In one embodiment an electric pulse to the firstpair of electrodes 14′ creates composition variation by ionizing oroxidizing a dissolved species in the fluid. The detection electrodes 14″will sense the variation by measuring oxidation-reduction current. It istherefore important to maintain accurate physical dimensions of thefeatures that affect the flow rates analysis. In one embodiment the hub16 is injection molded from a thermoplastic material such as PE, and theelectrodes 14 are insert-molded into the flight conduit 12 at preciselocations. In another embodiment the flight conduit 12 and theelectrodes 14 are embedded in a silicon or glass chip which isaccommodated in the fluid transport device 11.

Other flow measuring principals are applicable includingThermo-Time-Of-Flight mass flow meter, electronic flow switches,mechanical velocity meters, etc.

Referring now to FIG. 1 c the fluid transport device 11 of FIG. 1 a isshown together with a durable device 15, shown in a displaced positionfrom the hub 16. The durable device 15 comprises a package and at leastpart of the electronic circuitry for operating the sensor and forcommunicating the measurements data with a person or a device, and tabsfor electrically connecting to the tabs of the electrodes 14 in the hub16. In one embodiment the durable device generates the electric pulse atthe first electrode couples 14′ to generate a composition variation markin the flow. In one embodiment the durable device 15 operates the secondpair of electrodes 14″ for electroanalytically detecting the arrival ofthe mark. The circuitry of the durable device 15 will monitor currentbetween the second pair of electrodes as an indication of a change inconductivity which indicates the arrival of the mark. In someembodiments the durable device is powered by a rechargeable battery. Inone embodiment the flow control device (not shown) comprises a rechargedocking station for the durable device. In another embodiment the devicecomprises at least two rechargeable-battery operated durable devicessuch that at least one durable device 15 can be recharged while anotherdurable device 15 is in use. In another preferred embodiment of thepresent invention the durable device is powered by wires. In oneembodiment said wires are embedded in the fluid transport device leadingfrom an electric power source in the flow control device to the hub 16and terminating with connector tabs along side the electrode's 14 tabs.Alternatively the durable device can be powered by several other meansknown in the art including photovoltaic cells, motion converter,capacitor, or RF energy for example RF energy received by an RFIDcircuit, etc.

In one embodiment the durable device and the fluid control device areequipped with distance range detector and a warning circuitry in casethat the distance between the durable device 15 and the flow controldevice exceeded a predefined distance, for example to prevent accidentaldiscard or loss of the durable device in particular when the fluidtransport device 11 is disposable and is intended to be discarded at theend of a medical procedure. In another scenario said out-of-rangearrangement alerts an unintentional/accidental disconnect of at leastpart of the fluid transport device which is connected to the patientfrom the flow control system,

Referring now to FIG. 1 d, the preferred embodiment of FIG. 1 c is shownwhere the durable device 15 is attached to the fluid transport device11, and is operating. The figure illustrates a wireless transmissionfrom the durable device 15 to the flow control device (not shown). Thedurable device can transmit actual flow rate values or raw orsemi-processed data to be processed by another device. In someconfigurations the durable device can be communicated-to for example forthe purpose of self-testing, setting alarm values, or setting the flowmeter to a specific flow rates range.

The durable device 15 is attached to the fluid transport device by oneor more of the means known in the art including mechanical snapengagement, rotation, quarter turn, adhesive, adhesive tape, screws,thread, tongue and groove, magnetic coupling, etc.

The communication means can be one or more of the means known in the artincluding RF, IR, magnetic induction, ultrasonic, or by-wires. In oneembodiment of the present invention the wire communication between theflow control device and the durable device 15 is through wires embeddedin the fluid transport device 11 leading from the flow control device tothe hub 16 and terminating with connector tabs along side theelectrode's 14 tabs. In one embodiment same wires are used for poweringthe durable device 15 and communicating between the durable device 15and the flow control device.

The communication protocol of the durable device can includeidentification of the durable device 15 to avoid influence of otherdurable devices active in the range from interfering.

Referring now to FIG. 1 e a section view of the hub 16 is demonstratedwith a schematic presentation of the general functional circuitry of thedurable device 15. The electrodes 14 are reaching through the wall ofthe flight conduit 12 to contact the fluid. The distal end of theelectrodes 14 are in contact with the circuitry of the durable device15. In one preferred embodiment a functional level layout of the durabledevice 15 comprises a ‘female’ connector for communicating with a ‘male’connector in the hub 16, a controller, and a RF module for communicatingwith a flow control device.

Referring now to FIG. 1 h a circuit topology of the durable device 15 isdemonstrated. A sinusoidal waveform, with an amplitude between 0.01-1.0volts, is applied at a frequency of 30 Khz to drive terminals of aspecific geometry. The fluid responds based on its impedance, where theimpedance response of the fluid incorporating a marker is different fromthe reference response. The control circuitry can be more difficult todispose of due to cost and regulatory requirements.

The geometry of the flow conduit 12 and the sensor electrodes 14″ canaccommodate a wide range of flow rates and fluid chemistry. Differentmodules for specific flow detection applications can be accommodated.Such modules can be patterned with a series of identifiers such aselectrical contacts that can be automatically recognized by the durabledevice of the flow system.

Referring now to FIGS. 1 f and 1 g, an implementation of the circuitryof the disposable device in a PCB is demonstrated. FIG. 1 f demonstratesthe assembled position of the PCB having inlet an outlet nipplesconnecting to the fluid transport device (not shown). A connector 1 isdisposed on the surface of the sensor 11 for connecting the durabledevice (not shown). Two major layers of the PCB are demonstrated 5 and6. FIG. 1 g demonstrates an exploded view of the PCB 11. A flow channel12 is disposed between inlet cavity 2 and outlet cavity 3. Inlet cavity2 is in fluid communication with the inlet 7 which communicates with thenipple 9. Outlet cavity 3 is aligned and in fluid communication withoutlet 7 which is in fluid communication with a nipple 9. Conductivepattern 4 is printed on the substrate layers 5 and 6 electricallycommunicate the connector and the electrodes 14′ and 14″ which are influid communication with the flow conduit 12. In some embodiment furtherelectronic and electric components are embedded in the sensor circuitryas will be exemplified in the following figures. In some embodiments thefluid channel is interconnected with other fluidic devices which areembedded in or disposed over the PCB assembly. It will be obvious tothose skilled in the art that similar arrangement can be accomplished ona substrate such as in silicon, glass, or plastic. In one embodimentsuch circuitry is integrally produced by thin film chip manufacturingtechniques.

Referring now to FIG. 1 i, a further preferred circuit topology for theembodiment of FIG. 1 is demonstrated.

In this embodiment the disposable circuitry comprises isolationcircuitry as part of the disposable fluid transport device, and thedurable circuitry in the durable device comprises a control andprocessing circuitry separated. Isolation provided by capacitive meansis inexpensive and compact, hence can be included in the disposablemodule.

Referring now to FIG. 1 j, a further preferred circuit topology for theembodiment of FIG. 1 is demonstrated. In this embodiment the disposablecircuitry comprises isolation circuitry and sense amplifiers which areintegrated into the disposable fluid transport device. This arrangementreduces noise and allows the control circuitry in the durable circuitryto be located farther away from the disposable circuitry.

Referring now to FIG. 2, another preferred embodiment is shown where theflow meter is a Composition-Variation-Time-Of-Flight mass flow meter andwhere the flight conduit is implemented in a tube fitting 21, connectingbetween two portions of a tube 17 of the fluid transport device 11. FIG.2 a shows the durable device 15 removed from the fitting 21. Theelectrodes tabs 14 are clearly seen as well as the snap feature 22 ofthe fitting 21, for engaging the durable device 15. FIG. 2 b shows theembodiment of FIG. 2 a where the durable device 15 is engaged with thefitting 21 in the operable position.

Referring now to FIG. 3, a further preferred embodiment is demonstrated,where the flow meter is a Composition-Variation-Time-Of-Flight mass flowmeter and where the flight conduit 12 is implemented in a tube fitting37, connecting between two portions of a tube 17 of the fluid transportdevice 11. The durable device 32 comprises means for attaching to aninfusion pole 36 in a form of a clamp, and includes a Human MachineInterface (HMI).

The HMI of the durable device 32 comprises a seven segment display 33which shows the flow rate and other indications. The HMI furthercomprises buttons 34 for setting parameters and functions of the durabledevice 32 such as, units of measure to display, set or reset time of theprocedure, set or reset accumulated dose of the treatment, enter flowrates alarm values, reset alarms, view statistics, scroll betweenfunctions, etc.

The HMI can further comprise visual and audible indications such as LEDlights, buzzer, speaker or other means known in the art.

In one embodiment the durable device 32 can receive information fromother devices such as additional sensors, or information from the flowcontrol device and display this data.

In one embodiment the durable device 32 comprises means for shutting-offthe flow in the fluid transport device. In one embodiment at least aportion of said flow shut-off means is incorporated in the fluidtransport device 11. In one embodiment the flow stopping means is apinch valve (not shown) which has a movable rigid section that can beadvanced to press on a flexible tube portion of the fluid transportdevice, thereby causing said tube portion to collapse and shut down thefluid passage. The flow shut-off means can be set to be activated if asuspect of malfunction in the flow control device has been detected.Said movable part can be manipulated by a motor, a motor and a gear,piezo actuator, a solenoid actuator, a spring, a combination of those orany other means known in the art.

In one embodiment the durable device 32 comprises means for regulatingthe flow in the fluid transport device 11. In one embodiment at leastportion of said flow regulating means is incorporated in the fluidtransport device 11. In one embodiment the flow regulating means is apinch valve (not shown) which has a movable rigid part that can beadvanced to press on a portion of a flexible tube of the fluid transportdevice, thereby causing said tube portion to collapse and narrow downthe fluid passage thereby limiting the flow rates. Said movable part canbe manipulated by a motor, a motor and a gear, piezo actuator, asolenoid actuator, a spring, a combination of those or any other meansknown in the art. The circuitry in the durable device 32 will set theflow restrictor according to the flow rates measurements establishing aclosed-loop control of the flow rates. The durable device can be set toa desired flow rate using the HMI or other communication means with thedurable device 15, and maintain said rate accordingly. The flowregulating means is particularly advantageous where the flow controldevice is merely an infusion bag and where the fluid is biased to thefluid transport device by merely gravitational force, or pressurizingmeans applying pressure to said infusion bag.

In one embodiment the durable device 32 is powered by a wall AC supply,adjusted by internal or external power converter.

In one embodiment the fluid transport device comprises an individualidentification means (ID) and the durable device comprises means foridentifying said ID. The identification means can be a barcode or RFIDor any other identification means known in the art. The identificationcan be used to prevent reuse of a disposable fluid transport device 11.The identification means can also identify compatibility of a fluidtransport device 11 to a particular administration application.

Referring now to FIG. 4 a another preferred embodiment of the presentinvention is demonstrated where the fluid transport device 11 is adedicated tubing set for a peristaltic infusion pump 41. The infusionset 11 comprises a dedicated pumping portion 42 integrated between twotube sections 17 of the fluid transport device 11, said pumping portioncommunicates with the pump 41 and is manipulated by the pump to advancefluid from a reservoir (not shown) to the administration means to thebody of a subject (not shown). The principal of operation of the flowmeter in this embodiment is a Composition-Variation TOF MFM as describedin FIG. 1, and its flight conduit 12 is preferably accommodated on thesame platform as the pumping portion 42. The durable device isincorporated in the pump and is engaged with the tabs 14 when thepumping feature 42 is engaged with the pump 41. The durable devicecommunicates with the pump circuitry to improve pumping accuracy. In oneembodiment the durable circuitry is implemented in the pump circuitry.

In one embodiment the data from the durable device 15 is used for selfdiagnosis and self calibration of the flow control device 42. In oneembodiment the program of the flow control device comprise a routine forperforming self calibration or self diagnosis of the pump. In anotherembodiment the diagnosis routine can be remotely activated by atechnician or a device. The last arrangement can contribute to asignificant cost reduction of operation and maintenance.

Referring now to FIGS. 5 a & b, a preferred embodiment of flow controlsystem is demonstrated in a schematic fashion. The sensor 51 is shownimplemented in a fitting having an inlet equipped with a female LuerLock connector and an outlet equipped with a mail Luer Lock connector.The inlet and outlet are connected to the upstream portion anddownstream tube portions 17 of the disposable fluid transport devicewhich in this case is a disposable infusion set. The fitting can beattached to the set by the manufacturer, or by the user. It can bepacked with the fluid transport device or separately. The sensorcommunicates with a circuitry 54 (shown schematically). A movable member55 having a first rigid pointer end 56 and a second end associated withan actuator (not shown) is controlled by the circuitry 54 such that itcan be moved toward or away from the tube 17.

FIG. 5 b demonstrates the flow control system after the controlcircuitry 54 causes the actuator to displace the movable member 55toward the tube 17 and against a reciprocal rigid backing (not shown)causing it to collapse and restrict the flow passage in the tube therebyreducing the flow rate or shutting down the flow, The figure furthershows schematic arrows emphasizing the ability of the system to performa closed loop control of the flow rate by: a) sensing the flow rate inthe fluid transport device, b) analyzing flow rates and comparing to adesired flow rate introduced to the system by a device or a person, andc) adjusting the flow rate by restricting the flow passage. In a furtherpreferred embodiment the fluid transport device comprises a normallyclose valve and the flow control system can manipulate the valve to openper the desired flow rate.

Accordingly, the present invention has been described with some degreeof particularity directed to the exemplary embodiment of the presentinvention, It should be appreciated, though, that the present inventionis defined by the following claims construed in light of the prior artso that modifications or changes may be made to the exemplary embodimentof the present invention without departing from the inventive conceptscontained herein.

What is claimed is:
 1. A flow rate meter, comprising: a. a disposablefluid transport device portion, including: i. a flow conduit having aninlet and an outlet, said flow conduit defining a flow channel; and ii.at least a first portion of a control circuitry which is operative toderive the flow rate, wherein said first portion includes a plurality ofelectrodes adapted to directly contact fluid when present within saidconduit; and b. a reusable interface connector removably attachable tosaid disposable fluid transport device portion, said reusable interfaceconnector including: i. a second portion of said control circuitryconnectable to said first portion; ii. a communications interface forestablishing feedback communication to a desired location.
 2. The flowrate meter of claim 1, wherein said first portion includes two pairs ofelectrodes.
 3. The flow rate meter of claim 2, wherein said pairs ofelectrodes are spaced apart axially along a length of said flow conduit.4. The flow rate meter of claim 3, wherein at least some of saidelectrodes measure oxidations-reduction current.
 5. The flow rate meterof claim 1, wherein said flow rate meter is a composition variationtime-of-flight mass flow meter.
 6. The flow rate meter of claim 1,wherein said flow rate meter comprises one of a thermo-time-of-flightmass flow meter, an electronic flow switch, and a mechanical velocitymeter.
 7. The flow rate meter of claim 1, wherein said communicationsinterface comprises one of RF, IR, magnetic conduction, ultrasonic, andbi-wires.
 8. The flow rate meter of claim 1, further comprising a flowcontrol member.
 9. The flow rate meter of claim 1, wherein said reusableinterface connector comprises a clamp configured to attach to aninfusion pole, said reusable interface connector further comprising ahuman machine interface.
 10. The flow rate meter of claim 9, whereinsaid human machine interface comprises input buttons for settingparameters and functions of the reusable interface connector.
 11. Theflow rate meter of claim 9, wherein said human machine interfacecomprises at least one visual or audible indicator.
 12. The flow ratemeter of claim 1, wherein said flow conduit is part of dedicated tubingfor an infusion pump.
 13. The flow rate meter of claim 1, wherein saidflow conduit is part of a disposable infusion set.
 14. The flow ratemeter of claim 1, wherein said control circuitry is configured to sensethe flow rate through the flow conduit, analyze the flow rate, comparethe flow rate to a desired flow rate, and adjust the flow rate byrestricting said flow channel.